Zonal pathogenic community formation of gherkin hybrid cucumber under open ground conditions

Abstract

S.V. Bondarenko, I.M. Hordiienko, O.M. Bragin, T.A. Romanova, O.V. Romanov, R.M. Mamchur, L.M. Popova, ?.V. Kravchuk, I.A. Zhuravska, ?.A. Poedinceva, V.V. Horyainova, L.V. Zhukova, S.V. Stankevych* and O.V. Gepenko

The course of the research has been specified the regional list of Gherkin hybrid cucumber diseases. It is established that the dominant position in the pathogenic community of this vegeTable crop when growing under open ground conditions is occupied by the population of oomycetes representative (fungi-like organisms) – downy mildew or powdery mildew (Pseudoperonospora cubensis). In the research area, the nature of the dynamics of the primary disease's development and spread was actively changing, particularly downy mildew – from moderate to vigorous. Calculated correlation coefficients between the intensity of downy mildew spread and the main abiotic stress factors of June–July proved the direct dependence of this indicator on the decadal values of average daily and minimum air temperatures; the reverse dependence on the decadal maximum values of air temperatures, its relative humidity and "dew points". It is established that optimal for infection and re-infection of plants under conditions of the Left-Bank Forest-Steppe of Ukraine is a specific temperature regime of the first-second decades of July – with a sharp fluctuation of maximum and minimum temperatures, which maximally activates the process of moisture condensation from the air and forms the duration of preservation of drop-liquid moisture on the plant's leaf apparatus.

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